Refining discs with enlarged grooves



Aug. 14, 1962 D. R. DALZELL, JR 3,04

REFINING DISCS WITH ENLARGED GROOVES Filed Oct. 22, 1959 2 Sheets-Sheetl INVEVTOR. fiauzd 1?. Faye/Z; J2

1962 D. R. DALZELL, JR 3,049,307

REFINING DISCS WITH ENLARGED GROOVES Filed Oct. 22, 1959 2 Sheets-Sheet2 U v J g, INVENTOR.

Unite Filed Oct. 22, 1959, Ser. No. 848,147 4 Claims. (Cl. 241-255) Thisinvention relates to improvements in the art of refining fibrousmaterials and the like, and more particularly to improved discs for usein refiners of the attrition mill type. A particular refiner of thistype is disclosed and described in United States Letters Patent No.2,690,098, issued on September 28, 1954, to Dwight E. Jones and, forconvenience, the discs of the present invention will be described inconnection with such apparatus.

In the refining of fibers and the like it is the usual practice tosuspend the material to be reduced or defibered in a liquid, usuallywater, and then to pass the resulting suspension into refiningapparatus. In disc refining, the suspension is passed between parallel,relatively revolving discs provided with closely spaced, cooperatingworking faces having blades or raised projections over which thesuspension passes and which reduce the fibers by abrasion or cutting tothe desired form.

It is the principal object of this present invention to provide improveddiscs for use in such refiners. It has been discovered that improvedrefining results from having a maximum number of blades on the morerapidly revolving disc. However a minimum spacing between the blades isrequired in order to distribute the pulp suspension evenly over the discface. By means of the present invention, great improvement in the numberof effective blades is obtained substantially enhancing the refiningeffect of the discs.

The improvement according to this invention comprises a more rapidlyrevolving or propelling disc having blades arranged in circumferentialsegments, the blades within each segment being arranged in clustersextending across the Working face of the segment, with the blades Withineach cluster being separated by grooves and the clusters being separatedby enlarged grooves substantially wider than the grooves within theclusters.

Preferably the grooves on the rotating discs are between one-fourth andthree-fourths inches in depth, the narrow grooves are between aboutone-sixteenth and three-sixteenths inches in width, the enlarged groovesare between about one-fourth and three-fourths inches in width and arespaced between about one and three inches apart and the surface of theblades varies between about one-sixteenth and three-sixteenths inches inwidth. Also preferably, the other disc in each disc set is provided withgrooves which are of the same width as the narrow grooves in thepropelling discs.

For the purpose of illustration, a typical embodiment of the inventionis shown in the accompanying drawings in which:

FIG. 1 is a vertical cross-section of a refining machine with the discsmounted in place;

FIG. 2 is an exploded axial layout of the four refining discs of FIG. 1looking from inlet to discharge;

FIG. 3 is a plan view of a portion of disc 3;

'FIG. 4 is a section taken substantially on the line 4-4 of FIG. 3; and

FIG. 5 is a section taken substantially on the line 5-5 of FIG. 3.

The embodiment illustrated is shown in FIG. I mounted in the refiningapparatus disclosed in United States Patent No. 2,690,098. FIG. 1 hereinis substantially the refining end of the machine therein shown in FIG. 3and the discs herein indicated by the numerals 1, 2, 3 and 4 are thereinindicated by the numerals 102, 106, 104 and 100, respectively.

The fiber stock and the like, to be refined, generally consisting offibers suspended in water and usually under pressure, is fed into aninlet 5 and conveyed thence to the center of the first set of twocooperating discs 1 and 2. One of said discs rotates relative to theother. While this relative rotation can be accomplished by rotating thediscs in opposite directions or by rotating them at different speeds inthe same direction and such are included in the terms as herein used;No. 1 disc as shown is -stationary, while No. 2 disc is rotated in thedirection indicated by the arrow. The stock is propelled outwardlybetween discs 1 and 2 into the peripheral casing chamber 6 by thepressure of the fluid and by the action of a disc 2, hereinafter to bedescribed. From the casing chamber 6 the stock passes between thecooperating refining discs 3 and 4, disc 4 being herein shown asstationary while disc 3 is mounted to and rotates with the same rotor 7as disc 2. In flowing from periphery to center the stock again ispropelled by fluid pressure and by the action of disc 3, hereinafter tobe set forth. From the center 8 of disc 4 the refined stock passes tothe discharge 9.

The adjacent working faces of discs 1 and 2 and of discs 3 and 4 areprovided with blades 10 over which and between which the desiredrefining occurs. These blades are arranged in circumferential segmentsor section 11, the edges of which and extensions 12 thereof convergingtangential to a circle 13 having the center of the disc as its center.Due to the rotation of the rotating discs 2 and 3, the fiber stock ispropelled in a spiral path moving in the direction of rotation of saiddiscs, spiralling outwardly between discs 1 and 2 and inwardly betweendiscs 3 and 4. To materially enhance this movement of stock the bladesof discs 2 and 3 are disposed to propel the stock in the desireddirection, disc 2 having blades the segments of which are offset fromradial such that the inner ends of the blades lead the outer ends in thedirection of rotation while disc 3 has blades the sections of which areoffset in the opposite direction, that is, such that outer ends of theblades lead inner ends in the direction of rotation. Since it is therotating discs 2 and 3 which give both the radial and the circularcomponents ofmovement to the stock, these discs are herein calledpropelling discs.

It is apparent that without a countering force, the fiber stock in thegrooves of the rotating discs would merely move outwardly in the groovebetween the blades without being subjected to refining action. Thiscountering force is supplied by the disposition of the cooperatingblades of said other or stationary discs 1 and 4 which op erate to causethe fibers to move out of the grooves and across the blade where theyare refined. For this purpose the blades or the stationary discs shouldbe disposed substantially perpendicular to the path of thefiherstock asit moves spirally between the discs. This is accomplished by olfsettingthe blade sections from radial in the same direction as the cooperating,rotating discs inthe same disc set; that is, disc 1 has sections offsetsuch that inner ends of the section edges lead outer ends in thedirection of rotation of disc 2 and disc 4 has section edges offset suchthat outer ends lead inner ends in the direction of rotation of disc 3.This disposition is obtained by offsetting the blade sections of discs 1and 4 from to 10 in the indicated directions while the rotating bladesections are offset tangentially from 5 to 25. In other terms, referringto FIG. 2, angles ABC may vary from 0 to while angles DEF may vary from5 to 25". Furthermore, the blades in the blade sections 11 of disc 2 arearranged parallel to the trailing edge of said sections while the bladesof disc 1 are arranged parallel to the leading section edges in thedirection of rotation of disc 2 and the blades of the blade sections 11of disc 3 are arranged parallel to the leading edge of the sectionswhile the blades of disc 4 are arranged parallel to the trailing sectionedges in the direction of rotation of disc 3. With the blades thusdisposed on cooperating working faces of the discs, the blades ofcooperating discs always intersect at an angle thus avoiding parallelismwhich would result in the loss of refining action. In addition, thenoise level of the machine is substantially reduced.

In accordance with this invention it has been found that the bestrefining is obtained by having a maximum number of blade edgesconsistent with the proper movement of pulp acros the faces of theblades. This is provided on the propelling discs by so spacing theblades 10 as to provide a majority of narrow grooves and a plurality ofspaced internal grooves 21 substantially enlarged in Width and extendingacross the working face of each segment. This groove arrangementprovides blades arranged in clusters within each segment therebyproviding a larger number of blades for improved refining, improvedstock distribution between coacting discs, and pressure control.

Preferably, in discs of commercial sizes, the surface of the blades 10should be between about one-sixteenth and three-sixteenths inches inwidth, the narrow grooves 20 should be between about one-sixteenth andthreesixteenths inches in width, the enlarged grooves 21 should bebetween about one-fourth and three-fourths inches in width and spacedabout one to three inches apart, the depth of all grooves being betweenabout one-fourth and three-fourths inches. In a specific example havingdiscs 42 inches in diameter, the blades 10 are three-sixteenths inchesin width, all grooves are five-sixteenths in depth, the narrow grooves20 are three-sixteenths inches in width, and the enlarged grooves 21 arethree-eighths inches in width and spaced one and five-sixteenths inchesapart. The spacing of the blades on the other or stationary discs '1 and4 is not as important but desirably the grooves therein are the samesize as the narrow grooves 20.

The operation of the cooperating disc faces is believed to besubstantially as follows. The pulp stock enters the groove spacesbetween the disc under the force of the fluid pressure and the bladedisposition above described. The stock is put into spiral motion by therotation and blade disposition of the propelling discs 2 or 3. Thismotion is resisted by the blades of the stationary disc 1 or 4respectively which resisting force causes the fibers to be forced out ofthe grooves not only by direct action but also by a pressuredistribution set up in the grooves, and to be forced between and acrossthe interacting and intersecting blade surfaces of the two coactingdiscs where refining by abrasion (heating) or cutting takes place. Forrefining the blades of a two-coacting disc should not intersect at anangle greater than about 50.

The number of blade sections 1'1 herein shown disposed circumferentiallyof the discs is 18. This number has been found to be a satisfactorycompromise between the desire to have as many as possible to keep theangle of blade intersection between the rotating and the stationarydiscs as nearly constant as possible and ease of manufacture.

To facilitate entry of the fiber stock between discs 1 and 2 and tofacilitate central discharge from discs 3 and 4, at least one recessspace 15 is provided at the inner portion of each blade section. Entryof the fiber stock between discs 3 and 4 at the periphery thereof ismaterially aided by beveling inwardly the outer ends of certain bladesat each blade section on each disc, herein illustrated with alternateblades beveled. These beveled edges providing entry passages areindicated at 18 (FIGS. 3 and 5). For the same reason, the smallest blade22 on rotating disc 3 is eliminated in each blade segment 11. Except forthe beveled edges 18 and blades 22, disc 2 is identical with disc 3.

While the normal tendency is to pump from center to periphery, nodifficulty has been encountered in pumping from periphery to center indiscs 3 and 4 due to the action disc 3 which must be rotating and due tothe fluid pressure at the circumference which has increased in passingbetween discs 1 and 2. Units of this type have been constructed to giveimproved refining with a small pressure drop through the refiner.

As disclosed in the aforesaid patent, the spaces between the stationaryand rotating discs are adjustable by selfcentering means which maintainsthe space between discs 1 and 2 substantially equal to the space betweendiscs 3 and 4, with yielding means to permit the rotating discs to moveoff-center in response to expected pressure in one of the spaces,produced for example by passage of a solid object.

It should be understood that the foregoing description is for thepurpose of illustration only and that this invention includes allmodifications falling within the scope of the appended claims.

I claim:

1. A propelling disc adapted for use in a refining machine havingcooperating, relatively rotating discs having blades on their adjacentfaces arranged in circumferential segments extending from the interiorto the exterior of the working portion thereof, said propelling dischaving blades within each segment arranged in clusters extending acrossthe working faces of said segments, the surfaces of the blades of saiddisc being flat and defining a common plane, the blades within eachcluster being separated by narrow grooves between about one-sixteenthand threesixteenths inches in width, the clusters being separated byenlarged grooves between about one-fourth and threefourths inches inwidth.

2. A propelling disc according to claim 1 further characterized inhaving grooves between about one-fourth and three-fourths inches indepth, and blade surfaces between about one-sixteenth andthree-sixteenths inches in width, said enlarged grooves being uniformlyspaced apart between about one inch to three inches.

3. For use in a pulp-refining machine of the disc type, a pair ofcoaxial refining discs one of which rotates relatively to the other soas to constitute a propelling disc, said discs having blades on theiradjacent faces arranged in circumferential segments extending from theinterior to the exterior of the working portions thereof, saidpropelling disc having the blades within each segment arranged inclusters extending across the working face of said segment, all of theblades of said propelling disc having flat surfaces defining a commonplane, the blades within each cluster being separated by narrow grooves,the clusters being separated by enlarged grooves substantially widerthan the grooves within said clusters, the other disc having blades withflat surfaces defining a common plane and having grooves all of whichare substantially of the same width as the narrow grooves of saidpropelling disc.

4. Refining discs according to claim 3 wherein said propelling disc hasgrooves about five-sixteenths inches in depth, blade surfaces aboutthree-sixteenths inches in width, narrow grooves about three-sixteenthsinches in 5 width, and enlarged grooves about three-eighths inches in104, width, said enlarged grooves being uniformly spaced about 261,099one and five-sixteenth inches apart. 2,03 5,994 2,968,444 ReferencesCited in the file of this patent 5 UNITED STATES PATENTS 145 676 20,083Natcher Apr. 27, 1858 1 23 55 6 Bowman June 14, 1870 Lehmann July 11,1882 Sutherland Mar. 31, 1936 Jones Jan. 17, 1961 FOREIGN PATENTSGermany Oct. 31, 1903 France May 26, 1884

